1. Field of the Invention
The invention relates to a method for following and controlling the progress of annealing during heat treatment of cold worked metals, and an arrangement for carrying out the method. More specifically, the invention relates to such a method and arrangement which uses the changing electrical resistivity of the cold worked metal during annealing as a process control parameter.
2. Description of Prior Art
Present annealing cycles, which are applied to a variety of metals and alloys, particularly steels, are based on past experience and post-process control methods such as mechanical testing and metallography. Such cycles do not allow for corrections during the actual annealing process itself. When the annealing of cold worked metals is followed and analyzed using, for example, hardness measurements, optical and electron metallography, density, X-ray diffraction and positron annihilation as described, for example, in P. Hautojarvi, J. Johannson, A. Vehanen, J. YliKauppila, P. Girard, and C. Minier: J. Phys. F., 1980, vol. 11, pp. 1337-45.; M. L. Johnson S. Saterlie, D. Boice, and J. G. Byrne: Phys. Status Solidi, 1978, vol. 48, pp. 551-54.; G. Dlubek, O. Brummer, and N. Meyendorf: Solid State Commun., 1978, vol. 27, pp. 1219-22.; and G. Dlubek, O. Brummer, and A. Alam: Solid State Commun., 1979, vol. 29, pp. 597-99., there is usually a requirement for sophisticated apparatus. In addition, these methods are either difficult or impossible to use for monitoring during annealing so that corrections cannot be made during annealing.